EP0058805A1 - Method and device for filling flexible packages such as bags - Google Patents

Abstract

1. A method of filling a flexible package, via the top, with easily flowing solid products by means of a gravimetric feed, characterized in that there is associated with the feed means an open circuit, comprising a gas stream descending inside the flexible package so as to produce a permanent overpressure inside the package which maintains the package inflated, and so as to produce a current of air permanently flowing to the outside which maintains the edges of the package at a distance from the feed means.

Description

The present invention relates to a method and a device for bagging all types of products, in particular divided solid products, granules or powders in flexible packaging, a device which will be called in the following "bagging mouth". The invention is particularly applicable to flexible packaging of the bag or pocket type in the category known as "open mouth", that is to say which are filled from above and whose opening is made over the entire upper surface, or also on bags or similar bags called pre-welded, which have a partially closed opening. The invention, which is particularly advantageous in filling bags of several hundred kilos, applies however to bags having capacities ranging from micro-packaging to maxi-bag.

During the filling operation, the flexible container must be kept upright and open. This problem is solved in the case of packaging provided with a valve on the side at a high point, such as the packaging of French patent 2,309,409; in this case, the bagging mouth consists of a horizontal spout. The filling is done by projection inside the bag, which rests and rests on the filling spout which plays the role of support. This filling system is rapid, but it cannot be used for filling "open mouth" bags, the field to which the present invention is addressed.

In fact, the known dispositis making it possible to fill bags with an "open mouth" must most often be provided with a system of collars or clamping bars intended to keep the flexible container straight, open during the operation of filling, which involves pneumatic cylinders or manual eccentrics. Controlling these devices in the succession of operations requires complicated equipment. In other techniques, the blowing of compressed air, already known and used in packaging, is used to keep the bags upright, rigid and open. We know thus the process and the device described in Belgian patent 831,977: the filling of large capacity bags is done by means of a tube of diameter adapted to the opening of the bag and which alternately introduces compressed air and product. If necessary, an evacuation of the excess air is implemented, in particular when it is loaded with dust.

The use of compressed air has the disadvantage of requiring very strict adjustment between the opening of the bag and that of the bagging mouth, the dimensions of which must correspond. This process is therefore not applicable to the category of bags known as open mouth, or pre-sealed.

In other devices, the blower and the suction alternate in the same tube; these devices also require the traditional use of collars or clamping bars to avoid collapse of the top of the bag, hence the presence of jacks, eccentrics, etc. ... and a system for stopping and controlling the various operations of intermittent blower and suction.

Generally, closed circuits are used as in FR 2 194 607 or US 3 040 490. Optionally, recirculation of the displaced air is established as in US 3 040 490.

It is therefore desirable to eliminate as much as possible the mechanical, pneumatic or hydraulic members of the known devices and thus to simplify maintenance and adjustments.

; One of the aims of the invention is to increase the filling rates by simplifying the gestures necessary for positioning before filling. This gain is all the more important as the flexible bags are larger, bulky and difficult to handle.

Another aim is to significantly reduce the costs of investment in bagging stations.

The object of the invention is therefore a method and a device for filling flexible packaging from above, such as bags of easily flowing products, such as divided, powdered or granulated solids, without there being any contact between the bag and the filling mouth.

According to the invention, a method of filling a flexible packaging from the top is implemented with solid products which flow easily by means of a gravimetric supply, characterized by the fact that the supply means combine an open circuit comprising a gas flow descending inside the flexible packaging, so as to create an overpressure inside the packaging which maintains the inflated packaging and to generate a continuous stream of air escaping towards the outside keeping the edges of the packaging away from the supply means.

Advantageously, this first downward flow is associated with a second upward flow independent of the downward flow so as to create a hood effect serving to take in the surrounding air with which the excess gas from the downward flow mixes. the packaging and to evacuate it, as well as the gases, odors and dust which come from the packaging during filling, without the need to use a filter.

According to the invention, the gas in a simple manner consists of pressurized or ventilated air, which makes it possible to save compressed air and eliminate the drawbacks which result therefrom.

The method according to the invention can be implemented by a device which also forms part of the invention and which is characterized by the fact that it comprises at least one internal tube (1,2) used for feeding the product solid and at the downstream flow and at least one concentric external tube (3) for the upward flow, the internal and external tubes (1, 2, 3) constituting the bagging mouth, and at least one gas generator (4).

The gas generator, in particular of compressed or ventilated air is generally of the turbine type and can deliver several thousand cubic meters per hour. According to one embodiment, two generators can be used which flow in opposite directions.

The flexible packaging is placed under the bagging mouth device, the latter penetrating into the interior as will be seen in FIG. 1, without clamping contact with the mouth. The flexible packaging is in a state of permanent overpressure and therefore stands upright vertically, open and swollen with excess air, and, which is an advantage of the invention, even when the diameter of the opening of the bag is very widely. larger than that of the packing mouth.

As the bag fills with the product, the excess air is evacuated through the external suction tube after mixing with the surrounding air.

The bag, once full, is evacuated without difficulty, because there is no mechanical member for clamping or spacing the bag during filling. The placement of a new bag, and its shaping are, for the same reasons, instantaneous.

The median tube 2 is connected to a source of ventilated or pressurized air in itself, avoiding any source of compressed air which cannot be used in the "open mouth" bag technique. Everyone knows that compressed air, when it relaxes, is only effective in a closed enclosure. Thus, by way of example, blowers of 1,200 m3 Jh at 3,000 m ³ / h were used to inflate a 500-liter cylindrical packaging made of flexible material.

The suction tube is connected to a device provided with adequate sanitation and not forming part of the invention. A network of pipes is preferably used, the air of which is sucked in by a paddle wheel turbine.

_- We choose the arrangements and dimensions of the tubes according to the use as we will see in the examples below, the arrangement in concentric tubes offering the advantage of being compact and offering construction facilities. The diameter of the feed tube is not necessarily strictly adjusted to the opening of the bag, which does not need fixing means, unlike the technique using compressed air.

According to the invention, the internal tube serving to supply the gas, and in particular the air, is preferably of frustoconical shape, the smallest section of the truncated cone being disposed the most downstream in the direction of the gas supply.

In this way, it facilitates the placement of the packages and their evacuation without hooking the lower edges of the tubes as if they were straight.

This characteristic does not necessarily apply to the external vacuum tube (s), more recessed than the others, not entering the packaging, and therefore not likely to retain the packaging during the automatic evacuation of the latter.

Furthermore, the device according to the invention advantageously has a fixed shaping guide (9), pre-adjustable in all directions, arranged under the bagging mouth, intended to wrap the packaging on three of its faces and to keep in place and improve its stability.

The device according to the invention may also have at least one additional internal tube, making it possible to introduce other products, the mixing of which with the main product is carried out during filling.

According to the invention, bagging can be carried out depending on the case, either in net weighings also called "pre-weighs", or in gross weighings also called "post-weighings". In the first case, the organs necessary for weighing are placed upstream of the filling device, and it is then advantageous to provide two separate tubes for supplying the product (1) and for supplying the compressed air or ventilated (2). In the second case, the packaging being filled rests directly on the platform of the scale. In this case, advantageously only a central tube is provided for the supply of product and the supply of compressed or ventilated air, which proves to be particularly economical.

The accompanying drawings illustrate, by way of non-limiting examples, the preferred embodiments of the device of the present invention.

We distinguish in Figure 1, the external appearance of the device of the invention during the filling of a flexible maxi-bag, thanks to the central supply tube 1, the median tube 2 used for the introduction of the air in the bag. The tube 3 is extended at 5 for the permanent evacuation of the air sucked towards a device not shown, ventilated air is continuously introduced at 4; the bagging mouth of the invention is fixed in a known manner to a reserve device such as a hopper shown in 6.

There is also shown in this figure a shaping guide 9.

In the embodiment illustrated in FIG. 2, it is preferable to choose the median tube 2 for blowing air slightly shorter than the central tube 1, in order to avoid a possible backflow of ascending air into the central tube in end drop in the mass of pre-weighed product. Thus, by the device of the invention, there is no risk of rising air which would be capable of influencing a rocker upstream. This weighing method is advantageously applied to products which may present a risk of fluidization by air.

In the other bagging method commonly used and called "gross weighed" or post-weighed link, a variant of the device of the invention is advantageously produced, shown in exploded view in FIG. 3a. The product descends through the central tube 1; the air from the fan 4 supplied by 1 is permanently blown, thus mixing with the product. This construction variant of the invention is economical since the central tube 1 replaces the tubes 1 and 2 of the general device; it is advantageously applied in the case of non-fluidisable products, granules or powders.

In an alternative embodiment shown in FIG. 3b, the central tube 1 which makes it possible to introduce the product, communicates with the blowing of air 4 and also with other annexed pipes 7 and 8 by which other products are introduced, whose mixing is carried out during the filling operation.

There are shown in Figures 4a and 4b two arrangements in which the air supply tubes and various products are not concentric or cylindrical, but here of rectangular section and may be any, and only joined at the end of the mouth d bagging.

Without departing from the scope of the invention, it is possible to replace the air with another gas when the products are sensitive to air; the gas chosen may possibly have bactericidal properties.

A significant advantage of the invention is to be able to fill, using a single device, bags to be filled from above, whatever the diameter of their opening.

In particular, the invention has been applied to the filling of bags containing several hundred kilos of fertilizer.

Claims (13)

1 °) Method for filling a flexible packaging from the top with solid products which flow easily by means of a gravimetric supply, characterized in that an open circuit, comprising a gas flow descending inside the flexible packaging so as to create an overpressure inside the packaging which keeps the packaging inflated, and to generate a stream of air escaping constantly towards the outside keeping the edges of the packaging away from the supply means. 2 °) Method according to claim 1, characterized in that one associates a second upward flow independent of the downward flow, so as to create a hood effect with respect to the first and to the surrounding air. 3 °) Method according to one of claims 1 and 2 characterized in that the gas flow consists of pressurized air. 4 °) Method according to one of claims 1 and 2, characterized in that the gas flow consists of ventilated air. 5 °) Device for implementing the method according to one of claims 1 to 4, characterized in that it comprises at least one internal tube (1,2) used for feeding the solid product and for l '' supply of downflow and at least one concentric outer tube (3) for the upflow, the inner and outer tubes (1, 2, 3) constituting the bagging mouth, and at least one gas generator (4), overpressed or ventilated. 6 °) Device according to claim 5, characterized in that it comprises two generators of gas flowing in opposite directions. 7 °) Device according to one of claims 5 and 6, characterized in that the internal tube used for the supply of gas is of frustoconical shape, of smaller section downstream. 8 °) Device according to one of claims 5 to 7, i characterized in that it has a guide guide (9) fixed, pre-adjustable in all directions, arranged under the bagging mouth. 9 °) Device according to one of claims 5 to 8, characterized in that it has at least one additional internal tube allowing the introduction of other products whose mixing, with the main product, is carried out during filling. 10 °) Device according to one of claims 5 to 9, characterized in that it has at least two separate tubes (1) and (2) for the supply of solid product and gas. 11 °) Device according to one of claims 5 to 9, characterized in that it has a single tube (1) for the supply of solid product and gas. 12 °) Application of the device according to claim 10 for filling in pre-weighed. 13 °) Application of the device according to claim 11 for filling in post-weighings.

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